In one embodiment, a biological information monitoring apparatus includes: an antenna assembly including at least one antenna, the antenna assembly being configured to be disposed close to an abject; a signal generator configured to generate a high-frequency signal; a coupling-amount detection circuit configured to detect coupling amount of near-field coupling due to an electric field between the object and the at least one antenna by using the high-frequency signal; and a displacement detection circuit configured to detect a physical displacement of the object based on change in the coupling amount of near-field coupling.